Copper is a naturally occurring metallic element required in trace amounts for human health, supporting functions like energy production and iron metabolism. However, the element can become toxic when exposure levels exceed the body’s ability to regulate and excrete it. Concerns about elevated concentrations frequently arise regarding residential water quality and the safety of using this water for daily tasks like bathing.
Sources of Copper in Residential Water Systems
The most common source of high copper levels in a home’s water supply is the corrosion of household plumbing materials. Copper pipes, fittings, and brass fixtures release the metal into water that remains stagnant within the system for several hours, such as overnight. This leaching process is accelerated by certain water chemistries, particularly water that is chemically aggressive.
Aggressive water often has a low pH (acidic), which dissolves the protective interior layer of the copper piping. Soft water, which is low in calcium and magnesium, also tends to be more corrosive. Additionally, high levels of dissolved oxygen or elevated water temperatures can increase the rate at which copper is released. Less commonly, copper may enter the water from the municipal source, originating from natural mineral deposits or industrial runoff.
How Copper Interacts with the Body During Bathing
When bathing, copper can interact with the body through three primary pathways, though the overall contribution to systemic exposure is generally low. The dermal route involves the absorption of dissolved copper ions through the skin. Healthy, intact skin acts as an effective barrier, and the amount of copper absorbed this way is minimal compared to dietary intake.
Warm water can increase skin permeability by opening pores, slightly facilitating the passage of contaminants. Absorption may also be greater if the skin is damaged or suffering from a pre-existing condition. The second pathway is inhalation, as warm bath water creates steam and aerosolized droplets. If copper is highly concentrated, a small fraction could be inhaled as an aerosol.
The third and most significant exposure pathway is accidental ingestion. This occurs when bathwater or shower spray is inadvertently swallowed, which is common with infants and young children. Swallowing water is the most direct way to introduce dissolved copper into the gastrointestinal tract, where it is absorbed into the bloodstream.
Health Implications of Elevated Copper Exposure
The health risks associated with elevated copper levels are primarily linked to ingestion, causing both acute and chronic effects. Short-term exposure to high concentrations, often from drinking water that has sat in corroded pipes, can lead to acute gastrointestinal distress. Symptoms include nausea, vomiting, abdominal pain, and diarrhea, which resolve once the source of the high-copper water is eliminated.
Prolonged exposure can lead to chronic systemic issues as the metal accumulates in tissues. While the body is designed to excrete excess copper, long-term overload can overwhelm this process, potentially damaging organs like the liver and kidneys. In severe cases, chronic toxicity may result in liver disease or kidney failure.
Genetic Vulnerability
A small portion of the population is genetically vulnerable to copper toxicity, notably individuals with Wilson’s disease. This rare inherited disorder impairs the body’s ability to excrete copper. For these individuals, elevated copper poses a greater risk, as the metal can accumulate to toxic levels in the brain and liver. High copper levels also cause aesthetic problems, such as blue-green staining on porcelain fixtures and discoloration of light-colored hair.
Identifying and Mitigating High Copper Levels
Homeowners concerned about copper should rely on professional water testing to accurately determine the concentration. It is important to test the “first draw” water—water that has been sitting in the pipes for at least six hours—as this reveals the maximum copper level from pipe corrosion. The EPA Action Level for copper in public water systems is 1.3 milligrams per liter (mg/L), which serves as a benchmark for corrective action.
Immediate Mitigation
If testing reveals elevated levels, an immediate strategy is to flush the pipes by running the cold water tap for 30 seconds to a minute before consumption. This flushes out the standing water that has absorbed copper. For a permanent solution, homeowners can install point-of-use filtration systems, such as reverse osmosis or specialized activated carbon filters, certified to remove copper.
Long-Term Solutions
Addressing the root cause of corrosion is an effective long-term strategy involving adjusting the water chemistry. If the water is acidic, a professional can install a neutralizing filter or chemical feed system to raise the water’s pH closer to neutral, slowing the corrosive leaching process. In rare cases of extreme corrosion, replacing the copper plumbing with non-corrosive materials like PEX or PVC may be necessary.